If you're interested in Lead and Gold or Trine, take a look at my reviews at those links. They're both great games. Lead and Gold has online multi-player, so it's an excellent choice for a gift pack to share with your Steam friends.

If you're unfamiliar with the games in the Indie Air Pack, take a look at my reviews of Altitude, DogFighter, and Plain Sight. These are all online multi-player games that I highly recommend as well.